A speaker device is typically manufactured such that a speaker unit configured to output a sound is mounted to an enclosure having a box shape. The sound of the speaker unit may be distorted since a sound generated in the front surface of a vibration plate and a sound generated in the rear surface of the vibration plate may interact with each other. Therefore, the enclosure may prevent the interaction between the front sound of the speaker unit and the rear sound of the speaker unit so that improved sound may be outputted. In addition, a resonance space placed inside of the enclosure may reinforce a low sound to improve sound quality.
However, there may be a number of limitations on mounting the speaker device to a vehicle. An enclosure having a large volume may be required to output a good sound, but it may be difficult to mount the enclosure having a large volume to an indoor space of a vehicle having a small space. In addition, the enclosure having a large volume may increase a weight of the vehicle, and may increase a manufacturing cost of the vehicle.